In recent years, cycloolefin resins have been broadly utilized as forming materials or the like for resin formed articles such as drug containers and medical instruments since they exhibit excellent transparency, low hygroscopicity, excellent heat resistance, excellent chemical resistance, and the like.
However, since the cycloolefin resin normally has high rigidity, conventional cycloolefin resin product exhibited inferior impact resistance and inferior durability against a steam sterilization treatment in some cases.
In order to solve the above problem, methods in which a cycloolefin resin and a styrene-based elastomer are used in combination to give a resin composition having more excellent toughness have been proposed.
For example, Patent Literature 1 describes a film that is obtained by thinning a resin composition that includes a cycloolefin resin and a styrene-based elastomer. In addition, the literature also states that the resulting resin formed article exhibits excellent transparency, impact resistance, and the like.
However, when the toughness was improved by adding a styrene-based elastomer to the cycloolefin resin, transparency originally included in the cycloolefin resin is decreased in some cases. In addition, the resulting resin composition had a tendency to exhibit decreased melt fluidity and poor formability.